Circuit breaker



Oct. 21,

J. M. CUMMING E'lAL CIRCUIT BREAKER Filed NOV. 2, 1938 4 Sheets-Sheet lAT1-ORNEl `Oct. 21, 1941. .1. M. CUMMING ErAL CIRCUIT BREAKER Filed Nov.2,y 1938 4 Sheets-Sheet 2 J. M. CUMMING ETAL CIRCUIT BREAKER Oct. 21,1941.

WITNESSESI QQQIM Oct. 21, 1941. J. M. CUMMING ET Al. 2,259,971

CIRCUIT BREAKER Filed Nov. 2, 1938 4 Sheets-Sheet 4 @la M BY ATTORNEYPatented Oct. 21, 1941 CIRCUIT BREAKER James M. Cumming, Turtle Creek,and Raymond H. Leitzel, Wilkinsburg, Pa., assignors to WestinghouseElectric & Manufacturing Company,

East Pittsburgh, Pa., vania a corporation of Pennsyl- ApplicationNovember 2, 1938, Serial No. 238,382

17 Claims.

Our invention relates to circuit interrupters and has particularrelation to circuit breakers having a high interrupting capacity. Theprincipal concepts of our invention have general applicability and maybe embodied in circuit breakers of any general type regardless of themedium in which the interruption takes place. However, they shall bedescribed herein as applied to an air circuit breaker of the typedisclosed in a copending application, Serial No. 238,122, filed November1, 1938, of John B. Mac- Neill assigned to the Westinghouse Electric 8:Manufacturing Company and now Patent No. 2,227,507, issued January '1,1941. The apparatus disclosed in this application was developed for aninterrupting capacity of at least 900,000 kilovolt amperes at 15kilovolts.

In high powercircuit breakers, the lforces exerted between the fixed andmovable contacts when a circuit is opened or closed are of considerablemagnitude. In particular, when a circuit is being closed, the movablecontact is thrust between the fixed contact fingers at a high speed andany portions of the finger contacts which happen to be in the path ofits movement are subjected to heavy impacts. It often happens that thecontact surfaces of the fingers are at a slight angle to the surface ofthe corresponding movable contact and under such circumstances they areoften damaged by the force of the shock and need be replaced. Inaddition, the contacts may be severely burned by the arc.

In apparatus constructed in accordance with the teachings of the priorart, of which we are aware, the replacement of the contacts is arelatively complex operation. The fixed contact fingers are customarilyattached to their support, usually a casting, by pins about which theypivot towards the movable contact. When the fixed contacts are burned ordamaged by the impact from the movable contact, the fingers are removedfrom the circuit interrupter and replaced by new ones. To accomplishthis object, the pivoting pins are first extracted from the casting andthe fingers. This is a difficult operation, particularly when the damageoccurs after the interrupter has been in service for a long time and thefingers cohere tightly to the casting. It often happens, however, thatwhen the movable contact engages the fixed contacts improperly, it notonly deforms thefingers but also bends the pins so that their extractionfrom the casting is a highly troublesome matter. The diiiiculties andinconveniences involved here are increased cumbersome structure havingnumerous juts, openings and crevices and even the most simple operationswith it demand tools of unusual character. It is, accordingly, an objectof our invention to provide a circuit interrupter arrangement in whichit shall be possible to replace deformed or damaged contacts withfacility.

Another object of our invention is to provide a circuit interrupterarrangement in which the fixed contacts shall be so mounted that theirreplacement shall offer little dimculty.

A further object of our invention is to provide a circuit interrupter inwhich the fixed contacts shall be mounted as a unit removable from theremainder of the apparatus with facility.

A more specific object of our invention is to provide a circuitinterrupter in which the bending of the elements about which the fingercontacts pivot shall in no way impede the replacement of the damagedfingers.

Another specific object of our invention is to provide a circuitinterrupter in which the fixed finger contacts shall be so mounted as tominimize the possibility of damage by reason of the impacts exerted bythe movable contact.

An ancillary object of our invention is to provide a simplifiedsupporting structure for the fixed contacts of a high power circuitinterrupter.

Another ancillary object of our invention is to prevent sparking at thecontacts of circuit interrupters by reason of movement ofthe contactassemblies under the attractive electromagnetic forces between theshunts.

More concisely stated, it is an object of our invention to provide acircuit interrupter so constructed that it shall require a minimum ofservicing.

According to our invention, the casting Whereby the fixed contactfingers are supported is divided into two separable sections. Onesection, which we may designate as the front section, is a cradlethrough which the fingers extend. The shunts are secured to the fingersand project through the other section, which we may designate as therear section.

The axes about which the xed finger contacts pivot are inseparablyattached to the contacts. In the preferred practice of our invention,the axes are in the form of pins which extend through the fingers in adirection parallel to the contacting surfaces. A ball is secured to eachof the pins within the fingers and prevents by the construction of thecasting. It is a large the pins from sliding out of the fingers. 'I'heopenings in the fingers wherein the pins and balls are secured aresuiciently large to permit free movement of the fingers relative to thepins and balls.

When the circuit breaker is assembled, the pins are supported inbearings which are dis- .posed in the region of separation between thefront and rear sections of the castings, a portion of the bearing beingdisposed in each section. The fingers are moreover mounted as a unitwith the front section. fingers are in any way damaged, it is onlynecessary to remove the front section of the casting. The front sectioncarries with it the contact fingers and their associated elements. Thebending of the pins is of no consequence, since the separation of thesections of the casting removes the pins from the bearings, togetherwith the remaining portions of the contact ngers.

The novel features that we consider characteristic of our invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and its method ofoperation, together with additional objects and advantages thereof, willbest be understood from the following description of a specificembodiment when read in connection with the accompanying drawings, inwhlich- Figure 1 is a view in front elevation, partly in section, of acircuit interrupter constructed in accordance with our invention;

Fig. 2 is a view in side elevation of the contact assembly of thecircuit interrupter shown in Fig. 1;

Fig. 3 is a view in plan of the Contact assembly shown in Fig. 2;

Fig. 4 is a view in perspective of a xed contact support constructed inaccordance with our invention;

Fig. 5 is a view in side elevation showing the detailed construction ofa xed contact nger and its pivoting pin; and

Fig. 6 is a view in section taken along the line VI-VI of Fig. 5.

The apparatus shown in the drawings comprises an arc extinguishingchamber 5 formed between composite metallic uprights 1 and 9 and coversII of insulating material secured to the uprights. Each upright 1 and 9consists of a channel beam I3 with transverse plates I5 welded to theedges of the lower opening in the channel. The transverse plates I5 havea total width less than that of the channel and longitudinal plates I1extend from the inner edges of the transverse plates forming betweenthem an elongated opening of smaller width than that of the channel. Theweb of eacli channel is provided With openings near its four corners andwith a central opening. Through the corner openings insulating bars I9of phenolic condensation material pass and on them the plates 2|,whereby an arc is broken up and deionized, are stacked. Cylindricalinsulators 23 and 24 abut the central openings and a conducting bar 25passes through the openings and the insulators.

The deionizing stack 2| is of the usual structure comprising verticaliron and copper plates with fislr paper insulating sheets between them.As it does not concern the present invention, it will not vbe describedhere in detail.

The longitudinal plates I1 extending from the channels I3 rest on baseblocks 21 to which they are secured. 'Ihe openings in the channels I3Hence when the face away from the deionizing stack 2| and cover plates29 are provided for these openings and the coextensive opening betweenthe plates I1. The channels I3 and the coextensive plates I1 thus formues through which the gases generated during the interruption of acircuit are exhausted.

The fixed current carrying contact assembly 3| and the fixed arcingcontact assembly 33 are mounted in a box shaped casting 35 which issupported below the left-hand upright 1 on parallel columns 31. Thelatter columns are preferably composed of a phenolic condensationmaterial. The upper ends of the columns 31 engage lips 39 projectingfrom the casting 35 and the lower ends are secured to a suitablesupporting frame 4|. The columns 31 are held laterally by blocks 43 and45 bolted respectively to the casting 35 and the frame 4|.

A large double walled beam 41 in the form of a right angle, with thewall spacing equal to the distance between the columns 31, is supportedby the columns 31 and by a pair of short columns 49 of similar material.The angle 41 is disposed with its sides 5I and 53 horizontal andvertical respectively. 'I'he horizontal sides 5| are secured at the endsto the centers of the long colstuds 81 projecting on umns 31 and theshort column 49 passes through the apex of the angle and engages lips 54projecting from the vertical sides 53. The vertical sides 53 of theangle are coextensive with the column 49. The columns 31 and 49 and theangle 41 are held laterally by blocks 55. 51 and 59 which are bolted tothe parts to which they are secured.

The horizontal sides 5| of the angle 41 serve as bearing supports forthe pins 6| and 63 which carry at their respective centers the movablecontact arm and the spring 61 whereby the arm is actuated. The arm 65and spring 61 are mounted so that they may pivot; about the axes of thepins. The width of the horizontal side 5I of the angle 41 is such thatthe Vertical side 53 is coextensive with the right-hand upright 9forming the arc extinction assembly 5.

The uprights 1 and 9 rest on the casting 35 and on the vertical sides 53of the angle 41. For this purpose a slab 69 is secured to the upper endsof the vertical sides 53. The slab 69 is fastened to the right-handblock 21 and thus supports the right-hand upright 9. The left hand block21 rests on an insulating washer 1| supported on a horizontal projection13 extending from the casting 35. Below the projection 13 a secondinsulating washer 15 is provided and the projection is secured to theblock 21 by a bolt y11 extending through the washers and the projectionand insulated from the projection by a sleeve 19.

From the upper surface of the casting 35 and from the slab 69 extendstuds 8| and 83 respectively, which are adjustable in height. Compositeboards having internal insulating faces are supported on the studs andsecured to horizontal both sides from the upright plates I1. A chamberextending from the deionizing stack 2| to the circuit interruptingcontacts 3|, 33 and 89 and 9| is thus formed between the boards. The arcis moved through the chamber into the deionizing stack 2|.

The specific structure of the are chamber does not concern the presentinvention. However, briefly, its walls are composed internally of brousinsulating material 85, in which inserts 93 of a refractory insulatingmaterial are disposed, and

externally of iron (not shown). In Fig. 1 the interior surface 85 of asingle wall is shown. The other wall is of similar structure but hasbeen removed for the purpose of showing the interior of the chamber.

Within the arc chamber, arc transfer horns 95 and 91. are provided. Thehorns are secured to the channels I3 and to the plates |1 coextensivewith the channels, the left hand horn 95 being fastened to studs 99which project outwardly from the faces of the left hand plates |1. Thetip of the left-hand horn is located immediately. adjacent to thecontact fingers |03 of the fixed arcing contact assembly 33.

The fixed current carrying contact assembly 3| is of composite structurecomprising a pair of contact fingers preferably composed of silverplated copper. The ends of the contact fingers |05 are slotted and inthe slots (not shown) flexible shunts |01 composed of thin ribbons ofcopper are fastened, preferably by sweating. At the other ends theshunts are bolted to a tail projection |09 integral with the casting 35.The fixed arcing contact assembly 33 is of similar composite structurecomprising the pair of contact fingers |03 which are also slotted attheir ends. The slots (Fig. 3) receive the strands of the shunts ||3which, in turn, are secured to the tail projection |09 of the casting35.

Each of the contact fingers |05 and |03 is provided with a pin ||5 whichpasses loosely through the body of the finger near the end to which theshunt is secured. The pin ||5 is substantially parallel to the contactsurface ||6 of the finger and extends at both ends beyond the sides ofthe fingers through which it penetrates. In addition to the opening ||1through which the pin ||5 passes, each finger is provided with anopening ||9 perpendicular to the contact surface ||6 which passesthrough the pin opening at its center. Before the pin ||5 is slippedinto its corresponding opening ||1, a ball |2| having a slot |23 thereincapable of receiving the pin is inserted in the opening perpendicular tothe contact surface I6. After this the pin ||5 is passed through theopening ||1 in the block and the opening |23 in the ball |2| and theball is secured to the pin by riveting or in any other convenientmanner. A pin ||5 is thus inseparably secured to each of the fingers |03and |05.

The casting 35 in which the fixed contact assemblies 3| and 33 aremounted is of composite structure consisting of a front section |25 anda rear section |21. The two sections |25 and |21, when the apparatus isassembled, abut each other over machined surfaces. They are fastenedtogether by bolts |29 which pass through bosses |3| extending out fromthe abutting surface of the front section |25 at its lower end and atits center, and the bolts engage correspondingly internal threadedbosses |33 in the abutting surface of the rear section |21. The frontsection |25 of the casting 35 is divided by a partition |35 into upperand lower chambers |31 and |39 which are open in front and through whichthe fingers |05 and |03, respectively, extend.

The fingers are disposed with their contacting surfaces ||6perpendicular to the partition |35 and, therefore, the pins ||5 attachedto the fingers are also perpendicular to this partition. The

ends of the pins ||5 which extend beyond the sides of the fingers |03and |05 are secured in bearings IM, |43 and |45 formed when the abuttingsurfaces of the sections |25 and |21 are in engagement, The bearings arecut into partition liu |35 and the upper and lower walls |41 and |49 and|5| and |53, respectively, of the front and rear sections of the castingat the abutting surfaces and are partly inthe front section |25 andpartly in the rear section |21. When the sections |25 and |21 areseparated, the pins ||5 are therefore entirely released. The fingers |03and |05 are, moreover, loosely attached to the pins Ill so that when thepins are mounted in the bearings, the fingers are capable of swivellngabout the balls |2| and pivoting about the pins as axes.

The rear section |21 of the casting 35 is provided with a partitionwhich extends from its rear towards the abutting surfaces and separatesthe shunts |01 and ||3 extending from the cooperative pairs of fingers|03 and |05, respectively. When current flows through the fixed contacts3| and 33, the current flow in the shunts |01 and ||3 tends to cause theshunts from the cooperative fingers to attract each other and thepartition |55 functions to prevent the shunts from coming intoengagement. If the shunts should be capable of moving towards each otherunder the forces of attraction they would tend to pivot thecorresponding fingers away from each other on the cooperative contact.This produces a decrease in the contact pressure at the movable contactsurface and slight sparks result. The material used for the casting 35is preferably bronze. To facilitate the passage of current, the tail |09of the rear sectionthrough which connection is made to the fixed contactassemblies 3| and 33 is plated with copper.

The cooperative fingers |03 and |05 of each of the Contact assemblies 3|and 33 are resiliently urged into engagement with the movable contacts89 and 9| when the circuit is closed. For this purpose the walls of thechambers |31 and |39 in the front section |25 of the casting 35 areprovided with hollow bosses |51 having narrow inner flanges |59. Withineach of the bosses |51, a cap |6| is supported. Each of the caps |6|extends outwardly to a considerable distance beyond the bosses and itsoutermost periphery is closed by a cover |63 provided with an opening inits center. The openings |65 in the covers |63 of caps |6| supported inthe horizontally opposite bosses |51 function as bearings for pins |61.Each pin |61 passes through a pair of fingers |03 and |05 in a directionperpendicular to their contact surfaces ||6. The openings in the fingers|03 and |05 are substantially larger than the diameters of the pins |61and the fingers are capable of easily sliding along the pins. Thelast-mentioned pins |61 are transverse to the pins ||5 about which thefingers |03 and |05 pivot and, therefore, pivotal motion of the fingersis a sliding motion along the pins |61. Helical springs |69 encircleeach of the pins |61 at both ends. Each spring |69 engages the cover |63of the cap |6| at one end and an indentation 1| in the finger |03 or |05at the other end. The springs |69 thus urge the fixed contact fingers|03 and |05 into engagement with the movable contacts 09 and 9| when thecircuit is closed. To prevent the fingers 03 and |05 from being urged soclose to each other, when the circuit is open, that they are damaged bythe movable contacts 89 and 9| during the closing operation, aninsulating washer |13 is provided on each of the pins |61 between thefingers.

The two sets of fixed contact fingers |03 and |05 and their associatedpins and springs are attached to the front section |25 of the casting.

If the lingers |03 or 05 should in any way be damaged, they may bereplaced without difliculty. In such a case, the bolts |29 whereby thesections |25 and |21 of the casting 35 are held together, and the boltswhereby the shunts |01 and ||3 are secured to the tail |09 of thecasting are released and the front section of the casting, together withthe contact assemblies 3| and 33, are disengaged from the rear section|21 of the casting. Since the pivot pins ||5 are released when the twosections of the casting are separated, no diiculty arises by reason ofbent pins nor is there any diliculty in replacing the damaged linger. Toaccomplish the latter object, the pins |61 on which the linger contacts|03 and |05 slide and the caps IBI are removed from the correspondingbosses |51 and the damaged lingers |03 or |05 are then separated fromthe front section |25.

In the construction in accordance with our invention, the lingers |03and |05 are less often damaged by the impact of the movable contacts 89and 9| than in the prior art arrangements. This situation arises becausethe caps |6| on which the pins |61 transverse to the pivot pins 5 aresupported provide spacings between the bearings for pins |61 which aresubstantially longer than in the prior art arrangements. For the sametolerances, therefore, the angle by which the linger contacts |03 and|05 deviate from the perpendicular position to the pins |61 issubstantially smaller. Since the damaging impacts on the lixed contacts|03 and |05 in general depends on the angle of deviation from theperpendicular, the decrease in this angle amounts to a substantialdecrease in the probability of damage.

The movable contact assembly 65 is of composite structure consisting ofa heavy steel support |11 to which a copper contact carrier |19 issecured. Near the upper end of the carrier |19 the movable arcingcontact 89 projects; the movable current carrying contact 9| extendsparallel to the arcing contact 89 from a position below the latter. Themovable contacts 89 and 9| are of the knife type adapted to be engagedand held lirmly by the corresponding resiliently pivoted lingers |05 and|03.

The movable current carrying contact 9| is composed of silver platedcopper and is preferably attenuated at its end |8| so as to limit thespace necessary for the contacts when in engagement. The movable arcingcontact 89 is similarly attenuated at its end |83 and in the attenuatedregion is provided with inserts |85 and |81 of an arc resistant silvertungsten alloy.

The fixed arcing contact fingers |03 project into the arc space 5 and,as has been explained, are adjacent to the tip |0| of the left-hand arctransfer horn 95. So as to expedite the movement of the arc into the arcspace, the horn 95 is slotted near its tip |0| and the movable contact89, when the circuit breaker is in the closed position, penetrates intothe slot.

The movable contact assembly is actuated by a rod |89 which may be movedin the usual manner by an electro-magnetic system. The specific movingstructure is not shown as it does not concern the present invention. Ingeneral, the rod |89 is pivotally connected to the actuating system atits lower end |9I. At its upper end |93 the rod engages the commonmovable pivot pin |95 of a pair of sets of lever arms |91 and |99. Theformer set |91 pivots about a fixed pin 20| secured to the verticalsides 53 of the angle 41 and the other, |99, about a pin 203 in thesteel support |11 of the movable contact assembly 65. Below the latterpivot pin 203 the circuit opening spring 61 is secured to a pivot pin205. The movable contacts 89 and 9| are disengaged from the fixedcontact lingers |05 and |03, respectively, by the action of the spring61 when the mechanism whereby the rod |89 is moved into and held in theclosed position is released. In opening the movable contact assembly 65strikes against a shock absorbing stud 201 and thus is not damaged.

When the circuit interrupter is in the closed position, the current isprimarily carried by the current carrying contacts |05 and 9| since theresistance between the arcing contacts |03 and 89 is relatively high.The current carrying contacts and the arcing contacts are so positionedin their respective supports that when the circuit breaker opens thecurrent carrying contacts |05 and 9| are lirst disengaged and then themovable arcing contact 89 is disengaged from the xed arcing lingers |03.An arc is, therefore, produced between the latter elements. When thecurrent carrying contacts |05 and 9| are opening, the current in each ofthe arcing lingers |03 is increasing. Since the current paths throughthe ngers are parallel and in the same direction, the elect of theresultant increasing magnetic lields is to cause the lingers to hold thecontact 89 more tightly until the moment for release as determined bythe moving mechanism arrives. The establishment of an arc at the currentcarrying contacts |05 and 9| by reason of the opening of the arcingcontacts |03 and 89 only a very slight lixed interval after the openingof the current carrying contacts is thus entirely precluded.

The iixed arcing contact lingers |03 are provided with inserts 209 and2| The inserts 209 are in the form of tips extending upwardly towardsthe tip |0| of the arc horn 95. The lixed arcing contact assembly 33 ismoreover so disposed in the casting 35 that the direction o1 the currentflow in it between the region of separation of the contacts |03 and 89and the point of connection of the power supply line at the instant ofinterruption is lirst at a Small angle to the horizontal and, as thepoint of interruption is approached, at an angle sharply approaching thevertical. The insert |81 of the cooperative movable contact 89 is alsoin the form of a. tip so positioned that it engages the inserts 209lwhen the contacts |03 and 89 are last in engagement during the openingoperation. The contour of the inserts |81 and 209 is such that at thepoint of linal disengagement, the sides of the inserts |81 and 209 forman acute angle having its apex at the extreme upper region of thecontacting surfaces ||6, the apex being also the point of lastengagement of the contacts 03 and |89. It happens, therefore, that inthe region of separation of the arcing contacts the current lioW is in asharp loop convex towards the tip |0| of the adjacent arc transformerhorn 95. For this reason when the arc is produced, it also is in a sharploop convex towards the tip, and since the electromagnetic eliect ofcurrent flowing in a loop is to increase the radius of curvature of theloop, the arc produced decreases its curvature towards the tip ||J| andis quickly transferred to the horn.

By the transfer of the arc to the horn |0I, the circuit through aninductance loop or blow-in coil is closed. The loop consists of verticalstraps 2|3 extending between the projection 13 of the casting 35 and theadjacent end of the rod 25 passing through the insulators 23 and 2l,vertical straps 2I5 extending from the remaining end of the rod 25, apair of rods 2H extending from the lower ends of the straps 2I5 outsideof the arc chamber 5 and metallic strips 2|! extending from theremaining ends of the latter rods 2H to the studs 95 to which the arctransfer horn 95 adjacent to the fixed arcing contact H3 is secured.When the arc is transferred to the horn 95, a circuit is completedthrough this loop which extends from the line connection to the fixedcontacts |03 through the straps 2| 3, the bar 25, the straps 2I5, therods 2H, the strip 2I9, the arc horn 95, the movable contact assembly 65to the other line connection. By the action of the inductive loop, thearc is now transferred to the other arc horn 91. Since the latter hornis connected to the right angle 41, the circuit through the inductiveloop is not broken and the movement of the arc continues upward until itpasses into the deionizing stacks 2| and is extinguished.

Although I have shown and described certain specific embodiments of myinvention, I am fully aware that many modifications thereof arepossible. My invention, therefore, is not to be restricted exceptinsofar as is necessitated by the prior art and by the spirit of theappended claims.

We claim as our invention:

1. A circuit controller comprising a pair cf finger contacts and acooperative contact to be engaged by said finger contacts, at least oneof said finger contacts having as a part thereof a pin which projectsbeyond the edges thereof and a supporting structure for said fingercontacts, said structure consisting of a pair of separable sections andforming in a portion of the region of separation between said sections abearing for the projecting portion of said pin permitting pivotal motionof said one finger, and said finger contacts being secured to one ofsaid sections in such manner that when said sections are separated saidfinger contacts are separated with said one section from the other saidsection.

2. A circuit controller comprising a pair of finger contacts and acooperative contact to be engaged by said finger contacts, at least oneof said finger contacts having as a part thereof a pin which projectsbeyond the edges thereof, a supporting structure for said fingercontacts, said structure consisting of separable front and rear sectionsand forming in a portion of the region of separation between saidsections a bearing for the projecting portion of said pin permittingpivotal motion of said one finger, and said finger contacts beingsecured to said front section in such manner that when said front andrear sections are separated said finger contacts are separated from saidrear section with said front section, and means forming a unit with saidfront section and said fingers for resiliently urging said one fingercontact toward the other finger contact.

3. A pivotal finger contact comprising a block of conducting material, apin passing through an opening provided in said block and having securedintermediate the ends thereof and in said block a ball preventing thedisengagement of said pin and block, said pin and ball being sodimensioned that said block may move freely relative thereto, wherebysaid block is capable of a swivel motion about said ball when said pinis supported in bearings.

4. A circuit interrupter comprising a contact member, a cooperatingpivoted finger contact comprising a block of conducting material havinga surface for engaging said contact member, a pivot pin passing throughan opening provided in said block substantially parallel to said surfaceand having secured intermediate the ends thereof and in said block aball preventing the disengagement of said pin and block, said pin andball being so dimensioned that said block may move freely relativethereto, whereby said block is capable of a swivel motion about saidball, and bearing means for supporting the ends of said pivot pin.

5. A circuit controller comprising a pair of iinger contacts, each ofsaid finger contacts comprising a block of conducting material having asurface at which electrical contact is to take place, a pin traversingsaid block in a direction substantially parallel to said surface andextending beyond the edges of said block and a bail secured in saidblock intermediate the ends of said pin, said pin and ball being sodimensioned as to permit free motion of said block relative thereto,supporting means for said finger contacts including bearing means forthe extending ends of the pins so disposed in said supporting means thatwhen mounted in said supporting means said blocks are capable of aswiveling pivotal motion causing the surfaces of electrical contact tomove towards each other, and a cooperative contact to be engaged by saidsurfaces.

6. A circuit controller comprising a. pair of finger contacts, each ofsaid finger contacts comprising a block of conducting material having asurface at which electrical contact is to take place, a pin traversingsaid block in a direction substantially parallel to said surface andextending beyond the edges of said block and a ball mounted in saidblock and secured to said pin intermediate the ends thereof, said pinand ball being so dimensioned as to permit free motion of said blockrelative thereto, supporting means for said finger contacts includingbearing means for the extending ends of the pins so disposed in saidsupporting means that when mounted in said supporting means said blocksare capable of swiveling pivotal motion causing the surfaces ofelectrical Contact to move towards each other, a cooperative contact tobe engaged by said surfaces and resilient means for urging said blocksinto engagement with said cooperative contact.

7. Apparatus according to claim 6 characterized by the fact that saidsupporting means is made up of two separable sections, one of saidsections supporting the blocks and the resilient means so that when itis separated from the other, the blocks, pins and resilient means areremoved as a unit therewith.

8. Apparatus according to claim 6 characterized by the fact that saidsupporting means is made up of two separable sections, one of saidsections supporting the blocks and the resilient means so that when itis separated from the other, the blocks, pins and resilient means areremoved as a unit therewith, and the bearing means being provided in theregion between the sections.

9. In a circuit interrupter, in combination, a pair of contact fingerspivotal towards each other, a pair of relatively flexible shuntconductors disposed substantially parallel to one another and connectedto the ends of said contact fingers which are on the opposite side ofthe pivots from the contact surfaces of the contacts, and means forpreventing said shunt conductors from moving towards each other underthe ac.

tion of forces produced by the current owing therein.

10. In a circuit interrupter, a pair of linger contacts mounted forpivotal movement toward each other and adapted to engage a movablecontact, each of said linger contacts having a pivot pin permanentlysecured thereto about which it is adapted to pivot, a supportingstructure for said nger contacts comprising separable sections one ofwhich is fixed and the other of which is removably mounted on the xedsection, said sections forming bearings for the contact pivot pins inthe region of separation of said sections, a supporting pin for saidnger contacts mounted in bearings provided by outboard bearing capssecured to the removable section, said supporting pin extending throughopenings provided in said iinger contacts and having its axis disposedtransversely with respect to the axes of said contact pivot pins, andspring means mounted on said removable section for biasing said fingercontacts toward each other.

11. A circuit controller assembly comprising a pair of iinger contacts,a cooperating movable contact movable into and out of engagement withsaid finger contacts, at least one of said 1inger contacts being capableof being pivoted towards the other and means for supporting said i'ingercontacts, characterized by the fact that the axis about which thepivoting takes place is a pin mounted in a supporting structure, saidpin loosely passing through said finger, said pin having intermediatethe ends thereof and in the interior of said linger means to permitswiveling and pivotal motion of said nger relative to said pm.

12. A pivotal finger contact comprising a block of conducting material,a pin passing loosely through an opening provided in said block, theends of said pin being mounted in a supporting structure, said pinhaving intermediate the ends thereof and in the interior of said blockmeans mounted on said pin to permit pivotal and swiveling motion of saidnger relative to said pin.

13. A circuit controller assembly comprising a pair of nger contacts, acooperating movable contact movable into engagement with said fingercontacts, at least one of said ringer contacts being capable of beingpivoted towardsthe other and means for supporting said iin'ger contacts,characterized by the fact that the axis about which the pivoting takesplace is a pin loosely passing through said-finger, the ends of said pinprojecting beyond the sides of said finger contact that are parallelthereto and being engaged by said supporting means which thus providesbearings about Which the pivoting takes place, a ball mounted on saidpin intermediate the ends thereof and in the interior of said fingercontact, said ball permitting a limited amount of swiveling motion ofsaid finger relative to said pin in addition to the pivoting motion ofsaid finger.

14. A circuit controller comprising a pair of finger contacts and acooperating movable contact movable into engagement with said ngercontacts, at least one of said nger contacts having a pin which looselypasses through said finger contact and projects beyond the edgesthereof, said pin having mounted thereon intermediate the ends thereofand in the interior of Said nger means for permitting swiveling andpivotal motion of said nnger contact relative to said pin, a supportingstructure for said nger contacts, said structure consisting of separablesections and forming in a portion of the region of separation betweensaid sections a bearing for the projecting portions of said pin.

15. A circuit controller comprising a, pair of nger contacts and acooperating movable contact movable into and out of engagement with saidnger contacts, at least one of said linger contacts carrying as a partthereof a pin assembly comprising a pin which loosely passes throughsaid finger contact and projects beyond the edges thereof substantiallyparallel to the surface of engagement of said finger contact, a ballmounted on said pin intermediate the ends thereof and in the interior ofsaid nger contact to provide swiveling as well as pivotal motion of saidlinger contact with respect to said pin, a supporting structure for saidfinger contacts, said structure consisting of separable sections andforming in a portion of the region of separation between said sections abearing for the projecting portions of said pin.

16. In combination in a circuit interrupter, finger contact meansdisposed to be engaged by a cooperating movable contact, a supportingstructure consisting of two separable sections, said sections beingsecured together in the assembly of said circuit interrupter, an elementextending across one of said supporting sections, said finger contactmeans being loosely mounted on said element, bearing means for saidelement comprising caps extending outwardly from the same supportingsection across which the element extends, said caps having bearingsurfaces at their outer ends for said element, said caps being mountedon said one section during assembly of the circuit interrupter so thatwhen the two cooperating sections of the supporting structure areseparated the finger contact means, said element, said bearing caps andsaid one section comprise a unit separable from said other section.

17. In combination in a circuit interrupter, ringer contact meansdisposed to be engaged by a cooperating movable contact, a supportingstructure, an element extending across said supporting structure onwhich said nger contact means is loosely mounted, the mounting beingsuch that said finger contact means are substantially perpendicular tosaid element, resilient means mounted on said element for urging saidnger contact means toward each other, bearing means for said elementcomprising caps extending outwardly from said supporting structure andmounted thereon during assembly of said circuit interrupter, said capshaving bearing surfaces at their outer ends for said element.

JAMES M. CUNHVIING. RAYMOND H.

